This invention relates to electromagnetic interference (EMI) shielding, and more particularly to an apparatus for cost-effectively creating a high quality EMI screen over a key panel.
If an electronic device, such as a television digital special effects device, contains sources of radio frequency or other electromagnetic interference, and also presents openings to the world outside of its chassis, it acts as a source of EMI. This is particularly true if the openings in its chassis have long dimensions; the longer the dimensions, the longer the wavelengths that can pass through the opening, and the greater the range of radiated frequencies that can escape into the environment. Conversely, the smaller the chassis openings are, the shorter the wavelengths have to be in order to escape. When the only frequencies that can escape are higher in frequency than any signals present in the instrument, the instrument ceases to be an EMI source.
Since EMI is regulated by the Federal Communications Commission (FCC) in the United States and even more strictly in the Federal Republic of Germany by the Verband Deutscher Elektrotechniker (Association of German Electrical Engineers), such transmissions may constitute an unacceptable behavior of the instrument that renders it unmarketable in a number of important countries.